1. Field of the Invention
The present invention relates to improvements in electric starters having two drive motors of which one serves in a first stage for the advance of an actuator via a fixed longitudinal nut driven in rotation by this first motor, while the actuator is driven in rotation in a second stage both by the first and second motor.
2. History of the Art
U.S. Pat. No. 2,302,680 discloses starters of the type similar to the present invention in which one of the motors serves for the advance of the actuator by rotation of a longitudinally fixed nut cooperating with an outer thread of a bushing mounted about the shaft of the armature of the main motor. The powers of the two motors are added in order to transmit an increased effort to the pinion of the actuator. Such a starter is complex as the auxiliary motor actuates the nut via a toothed bevel gear which is expensive to produce and delicate to assemble. Such a starter cannot allow the use of a reducer associated with the shaft of the armature of the main motor, with the result that the main motor must be of a large size.